Commit 3b1d92c5 authored May 06, 2007 by Mel Gorman Committed by Linus Torvalds May 07, 2007

Do not disable interrupts when reading min_free_kbytes

The sysctl handler for min_free_kbytes calls setup_per_zone_pages_min() on
read or write. This function iterates through every zone and calls
spin_lock_irqsave() on the zone LRU lock. When reading min_free_kbytes,
this is a total waste of time that disables interrupts on the local
processor. It might even be noticable machines with large numbers of zones
if a process started constantly reading min_free_kbytes.

This patch only calls setup_per_zone_pages_min() only on write. Tested on
an x86 laptop and it did the right thing.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 8da3430d

mm/page_alloc.c

+2 −1

Original line number	Original line	Diff line number	Diff line
	@@ -3199,6 +3199,7 @@ int min_free_kbytes_sysctl_handler(ctl_table *table, int write,
	struct file file, void __user buffer, size_t length, loff_t ppos)		struct file file, void __user buffer, size_t length, loff_t ppos)
	{		{
	proc_dointvec(table, write, file, buffer, length, ppos);		proc_dointvec(table, write, file, buffer, length, ppos);
			if (write)
	setup_per_zone_pages_min();		setup_per_zone_pages_min();
	return 0;		return 0;
	}		}